A weekly journal on architecture, anthropology and radiant based heating, ventilation and air conditioning. The role of indoor environmental ergonomics, industrial design, HVAC as a health care issue and other human factors in the design of indoor spaces.

December 18, 2012

New method for estimating thermal comfort in low-energy buildings at the design stage

18 Dec, 2012 10:37 CET Indoor environments that are too hot, too cold or draughty
create discomfort and lower human productivity. MSc (Tech) Riikka Holopainen
from VTT Technical Research Centre of Finland, has written a doctoral thesis on
a new method for estimating the actual level of human thermal comfort in
low-energy buildings. The method is also the first of its kind to be integrated
with a building simulation tool. Factoring in the different ways in which
buildings are used and the different kinds of people using them at the design
stage can help to improve energy efficiency and human comfort.

The Human Thermal Model (HTM) is a new technique developed
by Senior Scientist Riikka Holopainen from VTT in her doctoral thesis, which
can be used to design and create optimal indoor environments for low-energy
buildings. One of the novelties of the method is the fact that it allows
scientists to measure how different solutions are likely to affect human
thermal comfort and the energy efficiency of buildings at the design stage.

The model is based on the physiological thermal control
system of the human body, and it can be used to calculate the actual level of
human thermal comfort in both steady-state and transient thermal environments.
The thesis introduces the first ever mathematical application that integrates a
building simulation tool with human thermal sensation. The model also produces
information about previously complex comparisons, such as the effects of
different structural solutions and HVAC systems on human thermal sensation.

Earlier models for measuring the comfort of indoor
environments have not taken account of the human body’s own thermal control
system. These methods are also insufficient for designing passive and
zero-energy buildings. Models based on laboratory measurements, for example,
overestimate the heat perceived by humans in warm conditions and underestimate
it in cool conditions. They also factor in clothing as a hermetically sealed
unit similar to a diving suit.

Both internal and external factors affect human thermal
sensation. Internal factors include personal characteristics, anatomy, activity
level, whether work is physical, and clothing. External factors include room
temperature, which covers air and surface temperature, as well as air velocity
and relative humidity. Holopainen has demonstrated that the most important
factors contributing to thermal sensation and comfort are air and surface
temperature, activity level and clothing.

Ensuring building
optimisation and human comfort at the design stage

Indoor environments that are too hot, too cold or draughty
create discomfort and lower human productivity. Bed-bound patients in
hospitals, for example, spend a great deal of time lying still and therefore
need a sufficiently warm indoor environment and bedclothes. Checkout operators
in shops, on the other hand, may have to sit in heat in summer and in cold and
draughts in winter. Factoring in the different ways in which buildings are used
and the different kinds of people using them at the design stage can help to
optimise indoor environments and improve human comfort. Employees can also be
given clothing advice.

The Human Thermal Model is suitable for both new builds and
renovations. Engineering firms and the construction industry can now develop
their products to better meet the needs of different buildings and users.

In the future, the HTM and building automation systems will
work together to automatically regulate ventilation, heating and cooling
according to actual needs, incorporating human thermal comfort as an integral
aspect of workplace productivity enhancement.

Comments

New method for estimating thermal comfort in low-energy buildings at the design stage

18 Dec, 2012 10:37 CET Indoor environments that are too hot, too cold or draughty
create discomfort and lower human productivity. MSc (Tech) Riikka Holopainen
from VTT Technical Research Centre of Finland, has written a doctoral thesis on
a new method for estimating the actual level of human thermal comfort in
low-energy buildings. The method is also the first of its kind to be integrated
with a building simulation tool. Factoring in the different ways in which
buildings are used and the different kinds of people using them at the design
stage can help to improve energy efficiency and human comfort.

The Human Thermal Model (HTM) is a new technique developed
by Senior Scientist Riikka Holopainen from VTT in her doctoral thesis, which
can be used to design and create optimal indoor environments for low-energy
buildings. One of the novelties of the method is the fact that it allows
scientists to measure how different solutions are likely to affect human
thermal comfort and the energy efficiency of buildings at the design stage.

The model is based on the physiological thermal control
system of the human body, and it can be used to calculate the actual level of
human thermal comfort in both steady-state and transient thermal environments.
The thesis introduces the first ever mathematical application that integrates a
building simulation tool with human thermal sensation. The model also produces
information about previously complex comparisons, such as the effects of
different structural solutions and HVAC systems on human thermal sensation.

Earlier models for measuring the comfort of indoor
environments have not taken account of the human body’s own thermal control
system. These methods are also insufficient for designing passive and
zero-energy buildings. Models based on laboratory measurements, for example,
overestimate the heat perceived by humans in warm conditions and underestimate
it in cool conditions. They also factor in clothing as a hermetically sealed
unit similar to a diving suit.

Both internal and external factors affect human thermal
sensation. Internal factors include personal characteristics, anatomy, activity
level, whether work is physical, and clothing. External factors include room
temperature, which covers air and surface temperature, as well as air velocity
and relative humidity. Holopainen has demonstrated that the most important
factors contributing to thermal sensation and comfort are air and surface
temperature, activity level and clothing.

Ensuring building
optimisation and human comfort at the design stage

Indoor environments that are too hot, too cold or draughty
create discomfort and lower human productivity. Bed-bound patients in
hospitals, for example, spend a great deal of time lying still and therefore
need a sufficiently warm indoor environment and bedclothes. Checkout operators
in shops, on the other hand, may have to sit in heat in summer and in cold and
draughts in winter. Factoring in the different ways in which buildings are used
and the different kinds of people using them at the design stage can help to
optimise indoor environments and improve human comfort. Employees can also be
given clothing advice.

The Human Thermal Model is suitable for both new builds and
renovations. Engineering firms and the construction industry can now develop
their products to better meet the needs of different buildings and users.

In the future, the HTM and building automation systems will
work together to automatically regulate ventilation, heating and cooling
according to actual needs, incorporating human thermal comfort as an integral
aspect of workplace productivity enhancement.

Our Purpose

Established in 2004, The Journal of Indoor Environmental Quality (JIEQ) in conjunction with Healthy Heating serves as a technical interpreter and consolidator of academic research demonstrating the building and health sciences are inclusive elements. It provides professional development programs based on its analysis to application professionals such as architects, engineers, interior designers and related technicians.

Subscribe to the JIEQ

Visit www.healthyheating.com

Friends of Industry

Quotes

“The quality of housing conditions plays a decisive role in the health status of the residents, because many health problems are either directly or indirectly related to the building itself, the construction materials that were used, and the equipment or the size or structure of the individual dwellings.”
The World Health Organization

"Indoor environmental quality is in part a result of materials and methods of construction which has an influence on occupant health. For this reason, policies around health and construction cannot be treated separately and must be linked together." Source: Bean, R., IAQ Webinar Presentation, 2009

The HVAC system consumes 50-60% of the building energy cost and generates 80-85% of tenant complaints.
Source: U.S. General Services Administration, Public Buildings Service, Office of the Chief Architect

Good Design

“Industrial designers determine the form and interaction qualities of manufactured products...They study people at work, at home and in motion to create satisfying experiences with products from the kitchen and the office to the hospital and the warehouse…” Excerpt from the Industrial Designers Society of America (IDSA).

In our opinion, industrial design has been overlooked by the HVAC industry – illustrated by consumers facing difficulties selling homes with HVAC systems which have “beast in the boiler room.”

Be reminded by S. Claire Conroy from Residential Architecture, "It's time architects of every discipline understand residential architecture for what it really is: everyone's most intimate connection with architecture. It's not simply a “test bed”—it's a vessel for our lives on their most personal level. That makes the stakes very high indeed. No one is more discriminating and demanding than a residential client.”

"A lot of it has to do with how we are responding at a physiological level to what we see as we walk in through the door." Sarah Susanka, Architect

“Industrial designers determine the form and interaction qualities of manufactured products...They study people at work, at home and in motion to create satisfying experiences with products from the kitchen and the office to the hospital and the warehouse…” Excerpt from the Industrial Designers Society of America (IDSA).

"In any industry, one of the most important and difficult tasks is to explain a nuanced process to someone unfamiliar with the field. At its grass roots, design is a process like many others; it has theories, strategies and examples that can be explained on a general level. It’s not a matter of what type of information is given, but rather how it is presented and to what type of audience."
Speaking Design to Non-Designers, IDSA